Vehicle cooling systems may include a plurality of cooling components such as radiators, cooling fans, liquid coolant circulation system, etc. The different cooling components utilize power from the engine and/or from a battery for operation. Additionally, the cooling system may receive cooling air from a front end of the vehicle, for example, through an active grille shutter (AGS) opening, to assist in cooling the engine, the transmission, and other components of the under-hood region. Such front-end air flow may cause parasitic loss of engine power by adding aerodynamic drag when the vehicle is in motion.
Various approaches may be used to reduce vehicular aerodynamic drag due to AGS opening while providing cooling to vehicle components. One example approach for AGS adjustments is shown by Klop et al. in US 20140370795. Therein, the AGS comprises angularly displaceable vanes which may be actuated to an intermediate position between a completely open position (allowing maximum intake air flow) and a closed position (completely blocking intake air flow). An actuator coupled to the vanes may be adjusted based on engine speed in order to adjust the vane openings and thereby control the aerodynamic drag caused by the air flow through the AGS.
However, the inventors herein have recognized potential issues with such systems. In particular, controlling the AGS opening based on engine speed may result in conditions where engine cooling demands and vehicle aerodynamic drag are in conflict. As one example, during high engine speed and high engine temperature conditions, the AGS may be closed to reduce aerodynamic drag, however, this may result in optimal engine cooling not being provided to the vehicle components. As another example, during conditions such as an engine cold-start where the engine speed is low and retention of engine heat is desired, the opening of the AGS may result in some air entering through the front end of the vehicle causing a reduction in engine temperature. As yet another example, during wet conditions such as during rain, or while in a car wash, the AGS may not be opened to avoid water penetration into the engine. However, during such conditions active cooling may be required for engine temperature control. While other vehicle cooling components, such as the cooling fan and the coolant circulation system, may be utilized for vehicle cooling during such conditions, continual usage of such cooling components can add to the engine's parasitic losses. In particular, the added consumption of engine power or battery power may adversely affect engine fuel efficiency and performance.
In one example, the issues described above may be addressed by a method for a vehicle comprising: estimating a powertrain component cooling demand based on operating conditions; and responsive to the powertrain component cooling demand, concurrently adjusting each of a radiator fan speed, a coolant system pump output, a vehicle grille shutter opening, and a vent opening of vents coupled to an engine insulating enclosure. In this way, by including an insulated enclosure around a powertrain component such as one of an engine, a transmission, and a torque converter, heat loss from the component may be limited and vents on the sides of the enclosure together with active grille shutters, a radiator fan, and a circulating coolant system may be adjusted concurrently for synergistic powertrain cooling benefits.
As one example, a vehicle powertrain component such as the engine, or the transmission may be enclosed within an insulated enclosure comprising adjustable vents on one or more walls. Based on a desired temperature of the enclosed component, the vents may be opened to varying degrees to facilitate flow of cool air, drawn into the underhood area via vehicle active grills shutters (AGS), through the powertrain component within the enclosure. Opening of the AGS may be coordinated with the opening of the vents on the insulated enclosures to regulate an amount, rate, and temperature of ambient air flowing into the enclosed vehicle component(s). For example, during conditions when aerodynamic drag is likely to occur and engine cooling is desired, the AGS opening may be reduced to limit aerodynamic drag while the opening of enclosure vents is increased to increase flow of cooling air through engine components. In addition, the operation of additional cooling components such as a radiator fan positioned between the AGS and the insulated enclosure, and a pump for circulating coolant through different vehicle components, may be adjusted to assist in engine cooling. As another example, during cold-start conditions, both the AGS and the vents may be held completely closed to reduce heat loss from the engine, thereby facilitating expedited heating of the enclosed engine. Depending on cooling demands of the vehicle components, the vehicle cooling system may be operated in one of a plurality of modes, each with different combinations of settings for the AGS, the enclosure vents, and the various other engine cooling components. A controller may select a mode that meets the given cooling demand with the lowest parasitic losses while taking into account losses due to aerodynamic drag, as well as fuel and battery power consumption.
In this way, by enclosing vehicle powertrain components such as an engine within an insulated enclosure with adjustable vents, dissipation of heat during low temperature operations (such as during cold-start conditions) may be reduced. By preserving engine heat during such conditions, attainment of catalyst light-off temperature may be expedited thereby improving emissions quality. Also, during engine operation at higher temperatures, by opening the vents of the enclosure, heat may be effectively dissipated from the vehicle component thereby having a cooling effect. By coordinating the operation of the adjustable vents with the operation of a vehicle's grill shutter system, heat can be retained in the engine while aerodynamic drag at the vehicle is also reduced, providing synergistic cooling benefits. The technical effect of operating the vehicle cooling system in a selected mode wherein the settings for the various cooling system components (including the adjustable vents, the AGS shutters, one or more coolant pumps, and one or more cooling/radiator fans) is adjusted to meet the cooling demands while taking into account parasitic losses caused by power usage and aerodynamic drag. Therefore, parasitic losses may be reduced without compromising engine cooling. As a result, engine performance and fuel efficiency may be improved.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.